OUTBOARD MOTOR

Abstract

An outboard motor includes a cooling device which includes a supply passage supplying a cooling water taken into a lower unit to a cooling mechanism. A first shaft portion of the connecting mechanism has a cylindrical shape, is provided in an upper part of the lower unit, and has an axis coaxial with the axis of a drive shaft. A second shaft portion has a cylindrical shape, is provided in a lower part of an upper unit, and has an axis coaxial with the axis of the drive shaft. One shaft portion of the first and the second shaft portions is inserted into the other shaft portion to be pivotable relative to the other shaft portion. The drive shaft is inserted into the one shaft portion with a space. A part of the supply passage is formed of the space between the drive shaft and the one shaft portion.

Claims

1. An outboard motor comprising: an upper unit including a drive motor; a lower unit including a propeller shaft; a drive shaft configured to transmit a rotation of the drive motor to the propeller shaft; a connecting mechanism connecting the lower unit to the upper unit to be pivotable about an axis of the drive shaft; and a cooling device, wherein the cooling device includes a cooling mechanism provided in the upper unit and configured to cool an equipment requiring cooling including the drive motor by using cooling water, an intake port configured to take water outside the outboard motor into the lower unit as cooling water, and a supply passage provided from the lower unit to the upper unit and configured to supply the cooling water taken into the lower unit to the cooling mechanism, the connecting mechanism includes a first shaft portion having a cylindrical shape, provided in an upper part of the lower unit, and having an axis coaxial with the axis of the drive shaft, and a second shaft portion having a cylindrical shape, provided in a lower part of the upper unit, and having an axis coaxial with the axis of the drive shaft, and one shaft portion of the first shaft portion and the second shaft portion is inserted into the other shaft portion to be pivotable relative to the other shaft portion, the drive shaft is inserted into the one shaft portion with a space, and a part of the supply passage is formed of the space between the drive shaft and the one shaft portion.

2. The outboard motor according to claim 1, wherein the one shaft portion is the first shaft portion, the supply passage includes a lower supply passage provided in the lower unit and connecting the intake port to the space, the space, an upper supply passage provided in the upper unit and having one end side connected to the cooling mechanism, and a communication passage communicating between the space and the other end side of the upper supply passage, and a communication passage forming member forming the communication passage is provided at an upper opening portion of the first shaft portion.

3. The outboard motor according to claim 2, wherein the communication passage forming member includes a lid portion attached to the upper opening portion of the first shaft portion, a tubular portion extending upward from an outer periphery of the lid portion and covering an opening portion on the other end side of the upper supply passage, a shaft insertion hole provided in a center portion of the lid portion and into which the drive shaft is inserted, and a communication hole provided in an inner periphery of the lid portion and communicating between the space and inside of the tubular portion.

4. The outboard motor according to claim 3, wherein the tubular portion is fixed to the upper unit, and the lid portion is inserted into the first shaft portion to be pivotable relative to the first shaft portion.

5. The outboard motor according to claim 4, wherein a sealing member is provided between an outer periphery of the lid portion and an inner periphery of the first shaft portion.

6. The outboard motor according to claim 1, wherein the cooling device includes a water pump configured to send the cooling water taken into the lower unit to the cooling mechanism, and the water pump is disposed on a lower end side of the first shaft portion.

7. The outboard motor according to claim 1, wherein the cooling device includes a water pump configured to send the cooling water taken into the lower unit to the cooling mechanism, the water pump is a rotary variable displacement water pump including an impeller made of rubber, the impeller is fixed to the drive shaft and configured to rotate integrally with the drive shaft.

8. The outboard motor according to claim 1, wherein the cooling device includes a drain port configured to discharge the cooling water after flowing in the cooling mechanism to outside of the outboard motor, the drain port is provided in the lower part of the upper unit behind the second shaft portion.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0029] FIG. 1 is an explanatory diagram illustrating an outboard motor according to an example of the present invention as viewed from the left.

[0030] FIG. 2 is an explanatory diagram illustrating the outboard motor according to the example of the present invention as viewed from behind.

[0031] FIG. 3 is a cross-sectional view of the outboard motor cut along a line A-A in FIG. 2 as viewed from the left.

[0032] FIG. 4 is an enlarged cross-sectional view of a portion of the outboard motor in FIG. 3 including a speed reducer, a connecting mechanism, a steering motor, and a worm gear mechanism.

[0033] FIG. 5A is a cross-sectional view illustrating an upper unit of the outboard motor in FIG. 4, and FIG. 5B is a cross-sectional view illustrating a lower unit of the outboard motor in FIG. 4.

[0034] FIG. 6 is a cross-sectional view cut along a line B-B in FIG. 4 as viewed from above illustrating a middle case of the outboard motor and a steering motor and a worm gear mechanism disposed in the middle case.

[0035] FIG. 7A is a block diagram illustrating a configuration of a cooling device provided in the outboard motor according to the example of the present invention, FIG. 7B is a block diagram illustrating a configuration of another cooling device that can be provided in the outboard motor of the present invention, and FIG. 7C is a block diagram illustrating a configuration of still another cooling device that can be provided in the outboard motor of the present invention.

[0036] FIG. 8 is an enlarged cross-sectional view of a portion of the outboard motor in FIG. 3 including an intake port, a water pump, a speed reducer cooling chamber, and a heat exchanger.

[0037] FIG. 9A is an external view illustrating a communication passage forming member in the outboard motor according to the example of the present invention viewed from above, FIG. 9B is a cross-sectional view illustrating the communication passage forming member cut along a line C-C in FIG. 9A as viewed from the left, and FIG. 9C is a cross-sectional view illustrating the communication passage forming member cut along a line D-D in FIG. 9A as viewed from the front left.

[0038] FIG. 10A is a schematic diagram illustrating an overall configuration of an outboard motor of the related art, FIG. 10B is an explanatory diagram illustrating an enlarged view of a portion surrounded by a two-dot chain line in FIG. 10A, and FIG. 10C is an explanatory diagram illustrating an annular flow path in FIG. 10B as viewed from above.

DETAILED DESCRIPTION OF EXEMPLIFIED EMBODIMENTS

[0039] Generally, an outboard motor is provided with equipment that requires cooling (hereinafter, referred to as equipment requiring cooling) such as a power source for rotating a propeller. To cool the equipment requiring cooling, many outboard motors are provided with a cooling device that takes water (for example, seawater) outside the outboard motor into the outboard motor and uses the water as cooling water to cool the equipment requiring cooling. The cooling device includes an intake port provided on a lower part of the outboard motor (a portion positioned below the water surface), a supply passage for supplying water outside the outboard motor flowed into the outboard motor from the intake port to the equipment requiring cooling as cooling water, and a pump that sends the cooling water to the equipment requiring cooling via the supply passage.

[0040] When a cooling device is provided in an outboard motor having a structure in which a lower unit pivots relative to an upper unit as described above, an intake port is provided in the lower unit, and a supply passage is provided in the outboard motor to supply water flowed into the lower unit from the intake port to the equipment requiring cooling as cooling water. Here, since the equipment requiring cooling such as a power source for rotating a propeller is provided in the upper unit, it is necessary to provide a supply passage extending from the lower unit to the upper unit. As the lower unit pivots relative to the upper unit, when providing a supply passage from the lower unit to the upper unit, it is necessary to consider a structure of the supply passage so that pivoting of the lower unit does not interrupt the supply passage or pivoting of the lower unit does not impair flow of cooling water in the supply passage.

[0041] Therefore, in the outboard motor 1020 illustrated in FIGS. 10A to 10C, the intake port 1314 equivalent to an intake port is provided in a portion of the lower unit UB positioned below the water surface. The cooling water conduits 1302, 1303, and 1306 corresponding to supply passages for supplying water flowed into the lower unit UB from the intake port 1314 to the upper unit UA are overall provided from the lower unit UB to the upper unit UA. The above-described outboard motor 1020 is provided with the annular flow path 1316 so that even when a position of the outlet port of the first cooling water conduit 1302 is displaced by pivoting of the lower unit UB, connection between the first cooling water conduit 1302 and the second cooling water conduit 1304 is maintained via the annular flow path 1316.

[0042] However, in the outboard motor 1020, the annular flow path 1316 is formed in the outer periphery of the center column 1035 of the steering housing 1028 as illustrated in FIG. 10B. Therefore, a circumferential length of a circle traced by the annular flow path 1316 is equivalent to a circumferential length of the outer periphery of the center column 1035, and thus the annular passage 1316 may become long. Accordingly, there is a risk that pressure loss due to the cooling water flowing in the annular flow path 1316 becomes large.

[0043] The annular flow path in the outboard motor described in U.S. Pat. No. 10,800,502B (annular channel 316) has substantially the same structure as the annular flow path 1316 in the outboard motor 1020. Therefore, even in the outboard motor described in U.S. Pat. No. 10,800,502B, there is a risk that the annular path becomes long, and thus there is a risk that pressure loss due to the cooling water flowing in the annular flow path becomes large.

[0044] The present invention is made considering, for example, the problem described above, and an object of the present invention is to provide an outboard motor in which a lower unit pivots relative to an upper unit capable of reducing pressure loss in a supply passage that supplies cooling water from the lower unit to the upper unit and smoothly supplying the cooling water.

[0045] An outboard motor according to an embodiment of the present invention includes an upper unit that includes a drive motor, a lower unit that includes a propeller shaft, a drive shaft that transmits rotation of the drive motor to the propeller shaft, a connecting mechanism that connects the lower unit to the upper unit to be pivotable about an axis of the drive shaft, and a cooling device. In the outboard motor of the embodiment, the cooling device is provided in the upper unit and includes a cooling mechanism that uses cooling water to cool equipment requiring cooling including the drive motor, an intake port that takes water outside the outboard motor into the lower unit as cooling water, and a supply passage that extends from the lower unit to the upper unit and supplies the cooling water taken into the lower unit to the cooling mechanism. The connecting mechanism also includes a cylindrical first shaft portion provided in an upper part of the lower unit and having an axis coaxial with the axis of the drive shaft, and a cylindrical second shaft portion provided in a lower part of the upper unit and having an axis coaxial with the axis of the drive shaft. In the connecting mechanism, one shaft portion of the first shaft portion and second shaft portion is inserted inside the other shaft portion to be pivotable relative to the other shaft portion. The drive shaft is inserted into the one shaft portion via a space. A portion of the supply passage in the cooling mechanism is formed of the space between the drive shaft and the one shaft portion.

[0046] In the outboard motor of the embodiment, the drive shaft is inserted into the shaft portion disposed inward of the two shaft portions of the connecting mechanism, that is, of the first shaft portion and the second shaft portion. Since the drive shaft is a shaft that transmits rotation of the drive motor to the propeller shaft, it is necessary for the drive shaft to be rotatable relative to a shaft portion disposed inward of the two shaft portions of the connecting mechanism. Therefore, the drive shaft is inserted into the shaft portion disposed inward via the space, and an annular space exists between the drive shaft and the shaft portion disposed inward. In the outboard motor of the embodiment, a portion of the supply passage that supplies the cooling water taken into the lower unit to the cooling mechanism provided in the upper unit is formed of the annular space that exists between the drive shaft and the shaft portion disposed inward of the two shaft portions of the connecting mechanism.

[0047] A circumferential length of the annular space that exists between the drive shaft and the shaft portion disposed inward of the two shaft portions of the connecting mechanism is longer than an outer circumferential length of the drive shaft and shorter than an inner circumferential length of the shaft portion disposed inward of the two shaft portions of the connecting mechanism. Meanwhile, a circumferential length of a circle traced by the annular flow path 1316 in the outboard motor 1020 illustrated in FIGS. 10A to 10C is equivalent to a circumferential length of the center column 1035 disposed on an outer periphery side of the steering column 1046 disposed on an outer periphery side of the drive shaft 1024. Therefore, when a size of the connecting mechanism in the outboard motor of the embodiment is equal to a size of the connecting mechanism in the outboard motor 1020, that is, for example, when an inner diameter of the shaft portion disposed inward of the two shaft portions of the connecting mechanism in the outboard motor of the embodiment is equal to an inner diameter of the steering column 1046 in the outboard motor 1020 or an outer diameter of the shaft portion disposed outward of the two shaft portions of the connecting mechanism in the outboard motor of the embodiment is equal to an outer diameter of the center column 1035 in the outboard motor 1020, a circumferential length of the annular space that exists between the drive shaft and the shaft portion disposed inward of the two shaft portions of the connecting mechanism in the outboard motor of the embodiment is shorter than a circumferential length of a circle traced by the annular flow path 1316 in the outboard motor 1020. When the size of the connecting mechanism in the outboard motor of the embodiment is equal to the size of the connecting mechanism in the outboard motor described in U.S. Pat. No. 10,800,502B, the circumferential length of the annular space that exists between the drive shaft and the shaft portion disposed inward of the two shaft portions of the connecting mechanism in the outboard motor of the embodiment is shorter than a circumferential length of a circle traced by the annular flow path in the outboard motor described in U.S. Pat. No. 10,800,502B (annular channel 316). Therefore, according to the outboard motor of the embodiment, a portion of the supply passage is formed of the annular space that exists between the drive shaft and the shaft portion disposed inward of the two shaft portions of the connecting mechanism, so that the portion of the supply passage can be shorter than both the annular flow path 1316 in the outboard motor 1020 and the annular flow path in the outboard motor described in U.S. Pat. No. 10,800,502B (annular channel 316). Therefore, it is possible to reduce pressure loss caused by the cooling water flowing in the portion of the supply passage. Therefore, the cooling water taken into the lower unit can be smoothly supplied to the cooling mechanism provided in the upper unit.

EXAMPLE

[0048] An outboard motor according to an example of the present invention will be described with reference to FIGS. 1 to 9C. In the description of the example, directions of up (Ud), down (Dd), front (Fd), back (Bd), left (Ld), and right (Rd) follow arrows drawn at the lower left in FIGS. 1 to 6 and 8 to 9C.

Basic Configuration of Outboard Motor

[0049] FIG. 1 illustrates an outboard motor 1 according to an example of the present invention as viewed from the left. FIG. 2 illustrates the outboard motor 1 as viewed from behind. FIG. 3 illustrates a cross section of the outboard motor 1 cut along a line A-A in FIG. 2 as viewed from the left. FIG. 4 illustrates an enlarged view of a portion of the outboard motor in FIG. 3 including a speed reducer 12, a connecting mechanism 40, a steering motor 45, and a worm gear mechanism 51.

[0050] The outboard motor 1 is a device for propelling a boat, and as illustrated in FIG. 1, is mounted on a transom 120 of the boat. As illustrated in FIG. 3, the outboard motor 1 includes an upper unit 2 that includes a drive motor 3, an inverter 6, and the speed reducer 12, and a lower unit 21 that includes a propeller 22, a propeller shaft 23, and a rotation transmission mechanism 24. The lower unit 21 is disposed below the upper unit 2 and is connected to the upper unit 2. The outboard motor 1 includes a drive shaft 31 that extends in a vertical direction from the upper unit 2 to the lower unit 21.

[0051] The drive motor 3 is a power source for rotating the propeller 22 and is, for example, an AC motor. The drive motor 3 includes a rotor, a stator, and an output shaft 4 that outputs rotation of the rotor. The drive motor 3 includes a motor case 5. The output shaft 4 excluding an end that outputs power, the rotor, and the stator are accommodated in the motor case 5. The drive motor 3 is disposed in an upper part of the outboard motor 1. When the outboard motor 1 is mounted on the boat, the drive motor 3 is positioned above the water surface. The drive motor 3 is disposed so that an extension direction of the output shaft 4 is the vertical direction.

[0052] The inverter 6 is a device that controls driving of the drive motor 3. The inverter 6 includes an inverter body 7 in which a circuit that controls driving of the drive motor 3 and the like are provided, and an inverter case 8 in which the inverter body 7 is accommodated. The inverter 6 is disposed above the drive motor 3. The inverter 6 is mounted on the drive motor 3 via an inverter mounting member 10.

[0053] The speed reducer 12 is a device that reduces rotation of the output shaft 4 of the drive motor 3 and transmits the rotation to the drive shaft 31. The speed reducer 12 is disposed below the drive motor 3. As illustrated in FIG. 4, the speed reducer 12 includes a drive gear 13 and a driven gear 14. The drive gear 13 is coupled to a lower end of the output shaft 4 of the drive motor 3 and rotates integrally with the output shaft 4. The driven gear 14 is disposed in front of the drive gear 13. The driven gear 14 is coupled to an upper end of the drive shaft 31. The driven gear 14 meshes with the drive gear 13. A gear ratio between the drive gear 13 and the driven gear 14 (the number of teeth of the driven gear 14/the number of teeth of the drive gear 13) is greater than 1.

[0054] A middle case 15 is provided in the upper unit 2 of the outboard motor 1. The middle case 15 is disposed below the drive motor 3 and is attached to the drive motor 3. The middle case 15 accommodates the speed reducer 12, an upper part of the drive shaft 31, the steering motor 45 (described below), and a worm gear mechanism 51 (described below). Although detailed illustration is omitted, the middle case 15 is divided into an upper case portion that accommodates the speed reducer 12 and a lower case portion that accommodates the steering motor 45 and the worm gear mechanism 51, and is formed by coupling the upper case portion and the lower case portion with a fastening member such as a bolt.

[0055] As illustrated in FIG. 3, the propeller shaft 23 is disposed in a lower part of the outboard motor 1. When the outboard motor 1 is mounted on the boat, the propeller shaft 23 is positioned below the water surface. The propeller shaft 23 extends in a front-rear direction. The propeller 22 is coupled to a rear part of the propeller shaft 23 and rotates integrally with the propeller shaft 23.

[0056] The rotation transmission mechanism 24 is a mechanism that transmits rotation of the drive shaft 31 to the propeller shaft 23. The rotation transmission mechanism 24 includes two bevel gears 25 and 26 that mesh with each other. One bevel gear 25 is coupled to a lower end of the drive shaft 31 and rotates integrally with the drive shaft 31. The other bevel gear 26 is coupled to a front end of the propeller shaft 23, and the propeller shaft 23 rotates integrally with the bevel gear 26.

[0057] A lower case 27 is provided in the lower unit 21 of the outboard motor 1. The rotation transmission mechanism 24 and a front part of the propeller shaft 23 are accommodated in the lower case 27. An anti-cavitation plate 28 is provided at a portion of the lower case 27 positioned above the propeller 22. A steering case 29 is provided at an uppermost part of the lower case 27.

[0058] The drive shaft 31 is a shaft that transmits rotation of the drive motor 3 after being reduced by the speed reducer 12 to the propeller shaft 23. As described above, the driven gear 14 of the speed reducer 12 is coupled to the upper end of the drive shaft 31, and the drive shaft 31 rotates integrally with the driven gear 14. The bevel gear 25 of the rotation transmission mechanism 24 is coupled to the lower end of the drive shaft 31. The drive shaft 31 is disposed in front of the output shaft 4 of the drive motor 3. In the speed reducer 12, the drive gear 13 is coupled to the output shaft 4 of the drive motor 3, and the driven gear 14 disposed in front of the drive gear 13 is coupled to the drive shaft 31. Accordingly, rotation of the output shaft 4 of the drive motor 3 is transmitted to the drive shaft 31 disposed in front of the output shaft 4 of the drive motor 3.

[0059] By controlling the inverter 6, the drive motor 3 is driven and the output shaft 4 rotates. Rotation of the output shaft 4 is transmitted to the drive shaft 31 while being reduced by the speed reducer 12, thereby rotating the drive shaft 31. Rotation of the drive shaft 31 is transmitted to the propeller shaft 23 by the rotation transmission mechanism 24, thereby rotating the propeller shaft 23 and the propeller 22. Rotation of the propeller 22 generates thrust for the boat.

[0060] The outboard motor 1 includes a mounting mechanism 33 for mounting the outboard motor 1 on the boat. The mounting mechanism 33 is disposed in front of the upper unit 2. The mounting mechanism 33 includes a pair of left and right clamp brackets 34 that fix the upper unit 2 to the transom 120 of the boat, and a mount bracket 35 that connects the clamp brackets 34 to the upper unit 2. A front part of the mount bracket 35 is disposed between the pair of clamp brackets 34 and is coupled to the pair of clamp brackets 34 via a tilt shaft 39. An upper mount portion 36 that supports an upper part of the upper unit 2 is provided in an upper part of a rear part of the mount bracket 35. The upper mount portion 36 supports a portion of the upper part of the upper unit 2 positioned between the drive motor 3 and the inverter 6. A lower mount portion 37 that supports a lower part of the upper unit 2 is provided in a lower part of the rear part of the mount bracket 35. The lower mount portion 37 supports a portion of the lower part of the upper unit 2 disposed above a portion in which the driven gear 14 of the speed reducer 12 is disposed. The mount bracket 35 can pivot in the vertical direction about an axis of the tilt shaft 39 relative to the clamp bracket 34. Accordingly, the outboard motor 1 can be pivoted (tilted up, tilted down) in the vertical direction relative to the boat. Unlike a general swivel bracket, the mount bracket 35 does not have a structure for causing the outboard motor to pivot in the left-right direction. As described below, the outboard motor 1 has a function of causing the lower unit 21 to pivot in the left-right direction relative to the upper unit 2, so that an orientation of the propeller 22 in the left-right direction can be changed and the boat can be steered even when a structure for causing the outboard motor 1 to pivot in the left-right direction is not provided on the mount bracket 35.

Configuration Regarding Pivoting of Lower Unit

[0061] FIG. 5A illustrates the upper unit 2 separated from the lower unit 21 in the outboard motor 1 in FIG. 4. FIG. 5B illustrates the lower unit 21 separated from the upper unit 2 in the outboard motor 1 in FIG. 4. FIG. 6 illustrates the middle case 15 of the outboard motor 1 and the steering motor 45 and the worm gear mechanism 51 disposed in the middle case 15 cut along a line B-B in FIG. 4 as viewed from above.

[0062] The outboard motor 1 has a function of steering the boat by causing the lower unit 21 to pivot in the left-right direction relative to the upper unit 2. Related to such function, the outboard motor 1 includes the connecting mechanism 40, the steering motor 45, and the worm gear mechanism 51 as illustrated in FIGS. 4, 5A, 5B, and 6.

[0063] The connecting mechanism 40 connects the lower unit 21 to the upper unit 2 to be pivotable about an axis K of the drive shaft 31. As illustrated in FIG. 4, the connecting mechanism 40 includes a first shaft portion 41 provided in an upper part of the lower unit 21, a second shaft portion 42 provided in the lower part of the upper unit 2, and a bearing 43, and is formed by coupling the first shaft portion 41 to the second shaft portion 42 via the bearing 43 to be pivotable. More specifically, as illustrated in FIG. 5B, the steering case 29 is attached to the uppermost part of the lower case 27 provided in the lower unit 21 to cover an entire upper surface of the lower case 27. The first shaft portion 41 is provided in the steering case 29. The first shaft portion 41 is formed in a cylindrical shape having an axis coaxial with the axis K of the drive shaft 31, and extends upward from an upper surface of the steering case 29. Meanwhile, the second shaft portion 42 is provided in a lower part of the middle case 15 positioned in the lower part of the upper unit 2 as illustrated in FIG. 5A. The second shaft portion 42 is formed in a cylindrical shape having an axis coaxial with the axis K of the drive shaft 31. An inner diameter of the second shaft portion 42 is larger than an outer diameter of the first shaft portion 41. As illustrated in FIG. 4, the first shaft portion 41 is inserted into the second shaft portion 42 from below the second shaft portion 42. The bearing 43 is provided between an inner circumferential surface of the second shaft portion 42 and an outer circumferential surface of the first shaft portion 41. The first shaft portion 41 is coupled to the second shaft portion 42 to be pivotable about the axis K of the drive shaft 31 relative to the second shaft portion 42, and is also coupled to the second shaft portion 42 to not be shifted in the vertical direction relative to the second shaft portion 42. The drive shaft 31 is inserted into the first shaft portion 41 with a space 65. The drive shaft 31 is rotatable relative to the first shaft portion 41.

[0064] The steering motor 45 is a power source that causes the lower unit 21 to pivot relative to the upper unit 2, and is, for example, a DC or AC motor. As illustrated in FIG. 5A, the steering motor 45 is provided in the upper unit 2 and is disposed in the middle case 15. As illustrated in FIG. 4, the steering motor 45 is disposed below the drive motor 3 and behind the drive shaft 31. When the outboard motor 1 is viewed from above, at least a portion of the steering motor 45 overlaps with the drive motor 3. The steering motor 45 is disposed behind the worm gear mechanism 51 and is disposed behind a worm wheel 53 and a worm 52. The steering motor 45 includes a rotor, a stator, and an output shaft 46 that outputs rotation of the rotor. As illustrated in FIG. 6, the steering motor 45 is disposed so that an axis L of the output shaft 46 is positioned on a plane perpendicular to the axis K of the drive shaft 31. The steering motor 45 is disposed so that an extension direction of the output shaft 46 is the left-right direction of the outboard motor 1. The steering motor 45 is mounted on a steering motor mounting portion 47, and the steering motor mounting portion 47 is fixed in the middle case 15.

[0065] The worm gear mechanism 51 is a mechanism that transmits rotation of the steering motor 45 to the lower unit 21 so that the lower unit 21 is pivoted relative to the upper unit 2. As illustrated in FIG. 4, the worm gear mechanism 51 is provided between the upper unit 2 and the lower unit 21. The worm gear mechanism 51 is disposed below the speed reducer 12. The worm gear mechanism 51 includes the worm 52 that rotates by rotating the steering motor 45, and the worm wheel 53 that meshes with the worm 52.

[0066] As illustrated in FIG. 5B, the worm wheel 53 is fixed to the steering case 29 provided in the lower unit 21. Specifically, the worm wheel 53 is fixed to an upper end of the first shaft portion 41 using a fastening member such as a bolt. As a result, the lower unit 21 pivots integrally with the worm wheel 53. The worm wheel 53 is disposed coaxially with the drive shaft 31 on an outer periphery side of the drive shaft 31. As illustrated in FIG. 4, the worm wheel 53 is positioned below the driven gear 14 of the speed reducer 12 in the middle case 15.

[0067] As illustrated in FIG. 6, the worm 52 is disposed behind the worm wheel 53 so that an axis M of the worm 52 extends in the left-right direction of the outboard motor 1. The worm 52 is disposed between the steering motor 45 and the worm wheel 53. The worm 52 is disposed so that the axis M is parallel to the axis L of the output shaft 46 of the steering motor 45. The worm 52 is mounted on the steering motor mounting portion 47 together with the steering motor 45.

[0068] A gear 54 is provided at a left end of the output shaft 46 of the steering motor 45. The gear 54 is coupled to the output shaft 46 and rotates integrally with the output shaft 46. A gear 55 is provided at a left end of a shaft portion of the worm 52. The gear 55 is coupled to the shaft portion of the worm 52, and the worm 52 rotates integrally with the gear 55. The gear 54 and the gear 55 mesh with each other.

[0069] By driving the steering motor 45, the output shaft 46 of the steering motor 45 rotates, the rotation is transmitted to the worm 52 by the gears 54 and 55, and the worm 52 rotates. Rotation of the worm 52 is transmitted to the worm wheel 53 so that the worm wheel 53 pivots. By pivoting of the worm wheel 53, the lower unit 21 pivots left or right relative to the upper unit 2. As such, by causing the lower unit 21 to pivot in the left-right direction, an orientation of the propeller 22 in the left-right direction can be changed and the boat can be steered. By causing the lower unit 21 to pivot 180 degrees left or right relative to the upper unit 2, the orientation of the propeller 22 can be changed by 180 degrees. Accordingly, it is possible to move the boat rearward without rotating the drive motor 3 reversely.

Cooling Device

[0070] FIG. 7A illustrates a configuration of a cooling device 61 provided in the outboard motor 1 of the example. FIG. 7B illustrates a configuration of another cooling device 101 that can be provided in the outboard motor of the present invention. FIG. 7C illustrates a configuration of still another cooling device 103 that can be provided in the outboard motor of the present invention. FIG. 8 illustrates an enlarged view of a portion of the outboard motor 1 of the example illustrated in FIG. 3 including an intake port 62, a water pump 77, a speed reducer cooling chamber 86, and a heat exchanger 87.

[0071] The outboard motor 1 includes the liquid-cooling cooling device 61 that cools the equipment requiring cooling provided in the outboard motor 1. Specifically, the equipment requiring cooling provided in the outboard motor 1 is the speed reducer 12, the drive motor 3, and the inverter 6.

[0072] As illustrated in FIG. 7A, the cooling device 61 includes the intake port 62, a supply passage, the water pump 77, a cooling mechanism 85, a discharge passage 81, and a drain port 83. The supply passage includes a lower supply passage 64, the space 65, a communication passage 66, and an upper supply passage 75.

[0073] The intake port 62 is a port that takes water outside the outboard motor 1 into the lower unit 21 as cooling water. The intake port 62 is provided in the lower unit 21. Specifically, as illustrated in FIG. 1, the intake port 62 is provided in a front part of the lower case 27 below the anti-cavitation plate 28.

[0074] The supply passage is a passage that supplies the cooling water taken into the lower unit 21 to the cooling mechanism 85. Since the intake port 62 is provided in the lower unit 21 and the cooling mechanism 85 is provided in the upper unit 2 as described below, the supply passage is provided from the lower unit 21 to the upper unit 2. As illustrated in FIG. 8, the supply passage is formed by sequentially connecting the lower supply passage 64, the space 65, the communication passage 66, and the upper supply passage 75.

[0075] The lower supply passage 64 is a passage that connects the intake port 62 to a suction port of the water pump 77. The lower supply passage 64 is provided in the lower unit 21. Specifically, the lower supply passage 64 is configured of, for example, a hole formed in the lower case 27. The lower supply passage 64 extends in the vertical direction between the intake port 62 and the suction port of the water pump 77. An upper end side of the lower supply passage 64 is connected to the space 65 via the suction port of the water pump 77, inside of a pump case 79 of the water pump 77, and a discharge port 80 of the water pump 77.

[0076] The space 65 exists between the drive shaft 31 and the first shaft portion 41. As described above, the connecting mechanism 40 has a structure in which the first shaft portion 41 is inserted inside the second shaft portion 42. The drive shaft 31 is inserted into the first shaft portion 41 with the space 65. The drive shaft 31 is rotatable relative to the first shaft portion 41. The space 65 between the drive shaft 31 and the first shaft portion 41 is a gap necessary for the drive shaft 31 to be rotatable relative to the first shaft portion 41. In the outboard motor 1, the space 65 between the drive shaft 31 and the first shaft portion 41 is used as a part of the supply passage. The axis K of the drive shaft 31 and an axis of the first shaft portion 41 each extend in the vertical direction, and the drive shaft 31 is inserted into the first shaft portion 41 to pass a center of the first shaft portion 41. Therefore, the space 65 between the drive shaft 31 and the first shaft portion 41 has an annular or cylindrical shape having an axis extending in the vertical direction.

[0077] The communication passage 66 is a passage that connects and communicates between the space 65 and the upper supply passage 75. The communication passage 66 is formed of a communication passage forming member 67 provided at an upper opening portion of the first shaft portion 41.

[0078] Here, FIG. 9A illustrates the communication passage forming member 67 as viewed from above. FIG. 9B illustrates a cross section of the communication passage forming member 67 cut along a line C-C in FIG. 9A as viewed from the left (bottom in FIG. 9A). FIG. 9C illustrates a cross section of the communication passage forming member 67 cut along a line D-D in FIG. 9A as viewed from the front left (lower left in FIG. 9A). In FIGS. 9A to 9C, the upper supply passage 75 is indicated by a two-dot chain line. In FIGS. 9B and 9C, the drive shaft 31, the first shaft portion 41, and the space 65 are indicated by two-dot chain lines.

[0079] The communication passage forming member 67 in the supply passage is a member that forms the communication passage 66 so that the space 65 between the drive shaft 31 and the first shaft portion 41 communicates with the upper supply passage 75. As illustrated in FIGS. 9A to 9C, the communication passage forming member 67 includes a lid portion 68 attached to the upper opening portion of the first shaft portion 41, a tubular portion 69 that covers an opening portion on an inlet end side of the upper supply passage 75, a shaft insertion hole 71 into which the drive shaft 31 is inserted, and a communication hole 72 that communicates between the space 65 and inside of the tubular portion 69.

[0080] The lid portion 68 is formed in a cylindrical shape having a diameter substantially equal to (strictly speaking, slightly smaller than) the upper opening portion of the first shaft portion 41. The lid portion 68 is disposed coaxially with the first shaft portion 41. The lid portion 68 is inserted into the first shaft portion 41 from above the first shaft portion 41 to be pivotable relative to the first shaft portion 41. As such, the lid portion 68 is attached to the upper opening portion of the first shaft portion 41 to cover the upper opening portion of the first shaft portion 41.

[0081] A sealing member 73 is provided between an outer periphery of the lid portion 68 and an inner periphery of the first shaft portion 41 to prevent cooling water flowed into the space 65 from leaking out of the space 65 from between the outer periphery surface of the lid portion 68 and the inner periphery surface of the first shaft portion 41.

[0082] The shaft insertion hole 71 is provided in a center of the lid portion 68 and passes through the lid portion 68. A diameter of the shaft insertion hole 71 is slightly larger than a diameter of the drive shaft 31. The drive shaft 31 inserted into the shaft insertion hole 71 is rotatable relative to the communication passage forming member 67.

[0083] The communication hole 72 is provided in an inner periphery of the lid portion 68 on an outer periphery side of the shaft insertion hole 71. The lid portion 68 is provided with a plurality of communication holes 72. Each communication hole 72 passes through the lid portion 68.

[0084] The tubular portion 69 extends upward from the outer periphery of the lid portion 68 while expanding in diameter. The tubular portion 69 has a roughly cup-like shape. As illustrated in FIG. 9A, a protruding portion 70 is formed in a portion of the outer periphery of the tubular portion 69 to protrude outward in a radial direction of the tubular portion 69. The opening portion on the inlet end side of the upper supply passage 75 is opened downward and faces the protruding portion 70. The tubular portion 69 is fixed to the upper unit 2. Specifically, as illustrated in FIG. 8, the tubular portion 69 is fixed to a partition wall portion 16 that covers the speed reducer 12 from below in the middle case 15 using a fastening member such as a bolt.

[0085] The communication passage forming member 67 is attached between the first shaft portion 41 and the partition wall portion 16 by fixing the tubular portion 69 to the partition wall portion 16 in the upper unit 2 and inserting the lid portion 68 into the upper opening portion of the first shaft portion 41. When the communication passage forming member 67 is attached between the first shaft portion 41 and the partition wall portion 16, a peripheral edge of the opening portion on the inlet end side of the upper supply passage 75 is covered by a peripheral edge of the protruding portion 70, and an inlet end of the upper supply passage 75 and inside of the tubular portion 69 of the communication passage forming member 67 are connected to each other. As such, by attaching the communication passage forming member 67 between the first shaft portion 41 and the partition wall portion 16, the space 65 and the upper supply passage 75 communicate with each other via each communication hole 72 of the communication passage forming member 67 and inside of the tubular portion 69. That is, the communication passage 66 that connects the space 65 to the upper supply passage 75 is formed of each communication hole 72 of the communication passage forming member 67 and inside of the tubular portion 69.

[0086] In the outboard motor 1 of the example, the tubular portion 69 of the communication passage forming member 67 has a function of forming the communication passage 66 and also has a function of forming the speed reducer cooling chamber 86 (to be described below).

[0087] As illustrated in FIG. 8, the upper supply passage 75 is a passage that connects the communication passage 66 to the cooling mechanism 85. The upper supply passage 75 is provided in the upper unit 2. The inlet end of the upper supply passage 75 is connected to the protruding portion 70 of the tubular portion 69 of the communication passage forming member 67. The outlet end of the upper supply passage 75 is connected to the heat exchanger 87 in the cooling mechanism 85. The upper supply passage 75 is formed of, for example, a hole formed in a right part of the middle case 15, and a hose or a pipe that connects the hole to the heat exchanger 87.

[0088] The water pump 77 is a pump that sends the cooling water taken into the lower unit 21 from the intake port 62 to the cooling mechanism 85. The water pump 77 is, for example, a rotary variable displacement water pump including a rubber impeller. The water pump 77 is disposed on a lower end side of the first shaft portion 41. An impeller 78 of the water pump 77 is disposed on an outer periphery side of the drive shaft 31. The impeller 78 is fixed to the drive shaft 31 and rotates integrally with the drive shaft 31. The pump case 79 that accommodates the impeller 78 is attached to, for example, the upper surface of the lower case 27. The water pump 77 is covered by the steering case 29 provided in the uppermost part of the lower case 27. An upper surface of the pump case 79 faces the space 65 between the drive shaft 31 and the first shaft portion 41. The discharge port 80 of the water pump 77 opens at the upper surface of the pump case 79 and the discharge port 80 communicates with the space 65.

[0089] The discharge passage 81 is a passage that transports the cooling water after flowing in the cooling mechanism 85 (in the heat exchanger 87) to the drain port 83. As can be viewed in FIGS. 1 and 4, the discharge passage 81 connects the heat exchanger 87 to a discharge chamber 82 provided in a lower part of a rear part of the middle case 15. The discharge passage 81 is formed of, for example, a hose or a pipe.

[0090] The drain port 83 is a port that discharges the cooling water after flowing in the cooling mechanism 85 (in the heat exchanger 87) to outside of the outboard motor 1. The drain port 83 is provided in the lower part of the upper unit 2 behind the second shaft portion 42. Specifically, the outboard motor 1 is provided with two drain ports 83. One drain port 83 opens to a left surface of the lower part of the rear part of the middle case 15, and the other drain hole 83 opens to a right surface of the lower part of the rear part of the middle case 15. Each drain port 83 communicates with inside of the discharge chamber 82. When the outboard motor 1 is viewed from the side, each drain port 83 is positioned below the steering motor 45.

[0091] As illustrated in FIG. 7A, the cooling mechanism 85 includes the speed reducer cooling chamber 86, the heat exchanger 87, a motor water jacket 88, an inverter water jacket 89, an electric pump 90, and a degassing tank 91. The cooling device 61 of the outboard motor 1 of the example basically includes a direct cooling system in which water outside the outboard motor 1 is supplied to the heat exchanger 87 and the water is used by the heat exchanger 87 to cool refrigerant (for example, a coolant such as LLC), and an indirect cooling system in which the refrigerant cooled by the heat exchanger 87 is supplied to the motor water jacket 88 and the inverter water jacket 89 so that the drive motor 3 and the inverter 6 are cooled by the motor water jacket 88 and the inverter water jacket 89. In the cooling device 61 of the outboard motor 1 of the example, the speed reducer cooling chamber 86 is connected to the direct cooling system, and water outside the outboard motor 1 passes the speed reducer cooling chamber 86 and is supplied to the heat exchanger 87. The water outside the outboard motor 1 passes the speed reducer cooling chamber 86, thereby cooling the speed reducer 12.

[0092] The speed reducer cooling chamber 86 is a chamber that cools the speed reducer 12 using the cooling water taken into the lower unit 21 from outside of the outboard motor 1 via the intake port 62. The speed reducer cooling chamber 86 is provided below the speed reducer 12 in the upper unit 2. Specifically, as illustrated in FIG. 8, the speed reducer cooling chamber 86 is formed in the middle case 15 between the partition wall portion 16 that covers the speed reducer 12 from below and the tubular portion 69 of the communication passage forming member 67 fixed to the partition wall portion 16. As can be viewed from FIG. 8, a portion of the space formed in the tubular portion 69 of the communication passage forming member 67 corresponds to the speed reducer cooling chamber 86.

[0093] The heat exchanger 87 is a device that cools the refrigerant that cools the motor water jacket 88 and the inverter water jacket 89 by using the cooling water taken into the lower unit 21 from outside of the outboard motor 1 via the intake port 62. As illustrated in FIG. 3, the heat exchanger 87 is disposed behind the drive motor 3 in the upper unit 2 and attached to the drive motor 3.

[0094] The motor water jacket 88 is provided in the drive motor 3. The motor water jacket 88 is configured of, for example, a refrigerant flow path provided in the motor case 5. The refrigerant cooled by the heat exchanger 87 flows in the motor water jacket 88, that is, in a flow path configuring the motor water jacket 88, thereby cooling the drive motor 3.

[0095] The inverter water jacket 89 is provided in the inverter 6. The inverter water jacket 89 is configured of, for example, a refrigerant flow path provided in the inverter case 8. The refrigerant after flowing in the motor water jacket 88 flows in the inverter water jacket 89, that is, in a flow path configuring the inverter water jacket 89, thereby cooling the inverter body 7.

[0096] The electric pump 90 is a pump that circulates the refrigerant in the heat exchanger 87, the motor water jacket 88, and the inverter water jacket 89. The electric pump 90 is disposed behind the inverter 6 in the upper unit 2 and is attached to the inverter 6.

[0097] The degassing tank 91 has a function of releasing air bubbles generated in the refrigerant due to heat or the like, and a function as a reserve tank to absorb any increase or decrease in the amount of the refrigerant due to thermal expansion or aging of the refrigerant. The degassing tank 91 is mounted on the inverter 6 via a plurality of degassing tank mounting portions 9 provided in the inverter case 8. Each degassing tank mounting portion 9 protrudes upward from an upper surface of the inverter case 8.

[0098] As illustrated in FIG. 1, the cooling mechanism 85 is provided with a connection passage 93 that connects the heat exchanger 87 to the motor water jacket 88 and supplies the refrigerant from the heat exchanger 87 to the motor water jacket 88. The connection passage 93 is formed of, for example, a hose or a pipe and is disposed on a left side of a rear part of the upper unit 2. The cooling mechanism 85 is provided with a connection passage 94 that connects the motor water jacket 88 to the inverter water jacket 89 and sends the refrigerant from the motor water jacket 88 to the inverter water jacket 89. The connection passage 94 is formed of, for example, a hose or a pipe and is disposed on an upper left side of the rear part of the upper unit 2. As illustrated in FIG. 2, the cooling mechanism 85 is provided with a connection passage 95 that connects the inverter water jacket 89 to the electric pump 90 and sends the refrigerant from the inverter water jacket 89 to the electric pump 90. The connection passage 95 is formed of, for example, a hose or a pipe and is disposed on an upper right side of the rear part of the upper unit 2. The cooling mechanism 85 is provided with a connection passage 96 that connects the electric pump 90 to the heat exchanger 87 and sends the refrigerant from the electric pump 90 to the heat exchanger 87. The connection passage 96 is formed of, for example, a hose or a pipe and is disposed in a portion of the upper unit 2 provided from behind the inverter 6 to behind the drive motor 3. The cooling mechanism 85 is provided with a connection passage 97 that connects the electric pump 90 to the degassing tank 91. The connection passage 97 is formed of, for example, a hose or a pipe and is disposed on the upper right side of the rear part of the upper unit 2.

[0099] As illustrated in FIG. 8, in the direct cooling system of the cooling device 61, when the water pump 77 is driven as the drive shaft 31 rotates, water outside the outboard motor 1 taken into the lower unit 21 from the intake port 62 flows in the lower supply passage 64 as cooling water and is sucked into the water pump 77 via the suction port of the water pump 77. The cooling water sucked into the water pump 77 is discharged from the discharge port 80 of the water pump 77 into the space 65 between the drive shaft 31 and the first shaft portion 41. The cooling water discharged into the space 65 flows in the space 65 and then flows in the communication passage 66. Specifically, the communication passage 66 is formed of the communication hole 72 of the communication passage forming member 67 and inside of the tubular portion 69. The cooling water after flowing in the space 65 first flows in the communication hole 72 and then flows in the tubular portion 69. As described above, a portion of the space in the tubular portion 69 of the communication passage forming member 67 serves as the speed reducer cooling chamber 86. The speed reducer 12 is cooled by the cooling water flowing in the tubular portion 69, that is, the cooling water flowing in the speed reducer cooling chamber 86. Then, the cooling water after flowing in the tubular portion 69 of the communication passage forming member 67 flows into the upper supply passage 75. The cooling water flowed into the upper supply passage 75 flows in the upper supply passage 75 and flows into the heat exchanger 87 of the cooling mechanism 85. The cooling water flowed into the heat exchanger 87 flows in the heat exchanger 87. Accordingly, the refrigerant of the indirect cooling system is cooled. The cooling water after flowing in the heat exchanger 87 flows in the discharge passage 81, flows into the discharge chamber 82, and is discharged from the drain port 83 to outside of the outboard motor 1.

[0100] In the indirect cooling system of the cooling device 61, by driving the electric pump 90, the refrigerant cooled by the heat exchanger 87 first flows in the motor water jacket 88. Accordingly, the drive motor 3 is cooled. The refrigerant after flowing in the motor water jacket 88 flows in the inverter water jacket 89. Accordingly, the inverter body 7 is cooled. Then, the refrigerant of which the temperature rose due to heat of the drive motor 3 and heat of the inverter body 7 passes inside of the electric pump 90 and is sent into the heat exchanger 87 to be cooled by the heat exchanger 87.

[0101] As described above, in the cooling device 61 provided in the outboard motor 1 of the example of the present invention, a portion of the supply passage that supplies cooling water from the lower unit 21 to the upper unit 2 is formed of the space 65 between the drive shaft 31 and the first shaft portion 41. By such configuration, the supply passage can be shortened, and pressure loss due to the cooling water flowing in the supply passage can be reduced. Therefore, cooling water can be smoothly supplied from the lower unit 21 to the upper unit 2.

[0102] Specifically, when a portion of the supply passage in the cooling device 61 provided in the outboard motor 1 of the example is formed of the space 65 between the drive shaft 31 and the first shaft portion 41 disposed inward of the two shaft portions 41 and 42 of the connecting mechanism 40, the portion of the supply passage can be made shorter than both the annular flow path 1316 provided in the outboard motor 1020 illustrated in FIGS. 10A to 10C and the annular flow path (annular channel 316 in U.S. Pat. No. 10,800,502B) in the outboard motor described in U.S. Pat. No. 10,800,502B. In other words, a circumferential length of the annular space 65 that exists between the drive shaft 31 and the first shaft portion 41 disposed inward of the two shaft portions 41 and 42 of the connecting mechanism 40 is longer than an outer circumferential length of the drive shaft 31 and shorter than an inner circumferential length of the first shaft portion 41. Meanwhile, a circumferential length of a circle traced by the annular flow path 1316 in the outboard motor 1020 illustrated in FIGS. 10A to 10C is equivalent to a circumferential length of the center column 1035 disposed on an outer periphery side of the steering column 1046 disposed on an outer periphery side of the drive shaft 1024. Therefore, when a size of the connecting mechanism 40 in the outboard motor 1 of the example is equal to a size of the connecting mechanism in the outboard motor 1020, that is, for example, when an inner diameter of the first shaft portion 41 in the outboard motor 1 of the example is equal to an inner diameter of the steering column 1046 in the outboard motor 1020 or an outer diameter of the second shaft portion 42 in the outboard motor 1 of the example is equal to an outer diameter of the center column 1035 in the outboard motor 1020, a circumferential length of the annular space 65 that exists between the drive shaft 31 and the first shaft portion 41 in the outboard motor 1 of the example is shorter than a circumferential length of a circle traced by the annular flow path 1316 in the outboard motor 1020. When the size of the connecting mechanism 40 in the outboard motor of the example is equal to the size of the connecting mechanism in the outboard motor described in U.S. Pat. No. 10,800,502B, the circumferential length of the annular space 65 that exists between the drive shaft 31 and the first shaft portion 41 in the outboard motor 1 of the example is shorter than a circumferential length of a circle traced by the annular flow path (annular channel 316 in U.S. Pat. No. 10,800,502B) in the outboard motor described in U.S. Pat. No. 10,800,502B. Therefore, according to the outboard motor 1 of the example, a portion of the supply passage is formed of the annular space 65 that exists between the drive shaft 31 and the first shaft portion 41, so that the portion of the supply passage can be shorter than both the annular flow path 1316 in the outboard motor 1020 and the annular flow path (annular channel 316 in U.S. Pat. No. 10,800,502B) in the outboard motor described in U.S. Pat. No. 10,800,502B. Therefore, it is possible to reduce pressure loss caused by the cooling water flowing in the portion of the supply passage. Therefore, the cooling water taken into the lower unit 21 can be smoothly supplied to the cooling mechanism 85 provided in the upper unit 2.

[0103] The cooling device 61 provided in the outboard motor 1 of the example includes the communication passage 66 that communicates between the space 65 and the upper supply passage 75, and the communication passage forming member 67 that forms the communication passage 66 is provided in the upper opening portion of the first shaft portion 41. By providing the communication passage forming member 67 in the upper opening portion of the first shaft portion 41, it is possible to prevent connection between the space 65 and the upper supply passage 75 from being interrupted by the lower unit 21 pivoting relative to the upper unit 2, or to prevent flow of the cooling water from being impaired between the space 65 and the upper supply passage 75. Specifically, the communication passage forming member 67 includes the lid portion 68 attached to the upper opening portion of the first shaft portion 41, the tubular portion 69 that extends upward from the outer periphery of the lid portion 68 and covers the opening portion on the inlet end side of the upper supply passage 75, and the communication hole 72 that is provided on the inner periphery of the lid portion 68 and communicates between the space 65 and inside of the tubular portion 69, in which the tubular portion 69 is fixed to the upper unit 2, and the lid portion 68 is inserted into the first shaft portion 41 to be pivotable relative to the first shaft portion 41. When the lower unit 21 pivots relative to the upper unit 2, the communication passage forming member 67 having such configuration pivots relative to the first shaft portion 41 while communication between the space 65 and the upper supply passage 75 via the communication hole 72 and inside of the tubular portion 69 is maintained. Therefore, when the lower unit 21 pivots relative to the upper unit 2, connection between the space 65 and the upper supply passage 75 is not interrupted and flow of the cooling water between the space 65 and the upper supply passage 75 is not impaired.

[0104] In the outboard motor 1 of the example, the sealing member 73 is provided between the outer periphery of the lid portion 68 of the communication passage forming member 67 and the inner periphery of the first shaft portion 41. Accordingly, the cooling water flowed into the space between the drive shaft 31 and the first shaft portion 41 is prevented from leaking from the supply passage in the upper unit 2 (specifically, in the middle case 15).

[0105] In the cooling device 61 provided in the outboard motor 1 of the example, the water pump 77 that sends cooling water to the cooling mechanism 85 is disposed on the lower end side of the first shaft portion 41. Accordingly, the discharge port 80 of the water pump 77 can be disposed at a position facing the space 65 below the space 65 between the drive shaft 31 and the first shaft portion 41. Therefore, the cooling water can flow directly from the water pump 77 into the space 65. Thus, the cooling water can be smoothly supplied to the cooling mechanism 85.

[0106] In the cooling device 61 provided in the outboard motor 1 of the example, the water pump 77 is a rotary variable displacement water pump including a rubber impeller, and the impeller 78 of the water pump 77 is fixed to the drive shaft 31 and rotates integrally with the drive shaft 31. A rotary variable displacement water pump including a rubber impeller has self-priming capability and high discharge pressure. Therefore, by using a rotary variable displacement water pump including a rubber impeller as the water pump 77, priming is unnecessary and cooling water can be stably supplied to the cooling mechanism 85. The outboard motor 1 can move the boat rearward without rotating the drive motor 3 reversely by causing the lower unit 21 to pivot 180 degrees relative to the upper unit 2. Therefore, in the outboard motor 1, problems such as impairment of the impeller 78 due to change in a rotation direction of the impeller 78 by switching between forward and reverse movement of the boat do not occur. That is, the rubber impeller can be severely impaired when a rotation direction of the impeller is changed. In an outboard motor in which the boat switches between forward and rearward movement by changing a rotation direction of the drive motor, when the rubber impeller of the water pump is fixed to the drive shaft so that the impeller rotates integrally with the drive shaft, every time the boat switches between forward and rearward movement, the rotation direction of the drive shaft changes, and as a result, the rotation direction of the impeller changes and the impeller is severely impaired. In contrast, the outboard motor 1 of the example can move the boat rearward by causing the lower unit 21 to pivot 180 degrees relative to the upper unit 2 without rotating the drive motor 3 reversely, so that even when the boat switches between forward and reverse movement, the rotation direction of the drive shaft 31 does not change, and the rotation direction of the impeller 78 does not change. Therefore, in the outboard motor 1, the impeller 78 is not impaired due to change in the rotation direction of the impeller 78.

[0107] In the outboard motor 1 of the example, the worm wheel 53 having a large diameter covers the entire upper opening portion of the second shaft portion 42 as illustrated in FIG. 4. By such structure, even when the cooling water flowing in the supply passage leaks from the supply passage in the middle case 15, the cooling water can be prevented from scattering and flowing toward the bearing 43 side.

[0108] The outboard motor 1 of the example is provided with the drain port 83 that discharges the cooling water after flowing in the cooling mechanism 85 to outside of the outboard motor 1, in which the drain port 83 is provided in the lower part of the upper unit 2 behind the second shaft portion 42. By providing the drain port 83 in the upper unit 2, a passage connecting the cooling mechanism 85 to the drain port 83 can be easily provided in the outboard motor 1 having a structure in which the lower unit 21 pivots relative to the upper unit 2. By disposing the drain port 83 at the lower part of the upper unit 2 behind the second shaft portion 42, the drain port 83 can be brought closer to the water surface outside the outboard motor 1. Accordingly, drainage noise can be reduced. In other words, noise generated by the cooling water being discharged from the drain port 83 and falling into the water outside the outboard motor 1 can be reduced.

[0109] The outboard motor 1 of the above-described example is provided with the cooling device 61 illustrated in FIG. 7A. However, the cooling device for the outboard motor of the present invention is not limited to the cooling device 61. For example, the outboard motor of the present invention may be provided with the cooling device 101 illustrated in FIG. 7B or the cooling device 103 illustrated in FIG. 7C instead of the cooling device 61. In a cooling mechanism 102 provided in the cooling device 101 illustrated in FIG. 7B, a flow direction of the refrigerant flowing in the heat exchanger 87, the motor water jacket 88, and the inverter water jacket 89 is opposite to that of the cooling mechanism 85 provided in the cooling device 61 illustrated in FIG. 7A. The cooling device 103 illustrated in FIG. 7C does not have a configuration that includes a direct cooling system and an indirect cooling system. A cooling mechanism 104 of the cooling device 103 is configured so that cooling water taken into the lower unit 21 from the intake port 62 is supplied to the speed reducer cooling chamber 86, the motor water jacket 88, and the inverter water jacket 89, thereby cooling the speed reducer 12, the drive motor 3, and the inverter 6.

[0110] The equipment cooled by the cooling device provided in the outboard motor of the present invention is not limited to the speed reducer, the motor, and the inverter. For example, only the motor may be cooled, or only the motor and the inverter may be cooled, or equipment other than the speed reducer, the motor, and the inverter may be cooled.

[0111] In the connecting mechanism of the outboard motor 1 in the above-described example, the first shaft portion 41 provided in the lower unit 21 is inserted into the second shaft portion 42 provided in the upper unit 2, but the connecting mechanism of the outboard motor of the present invention is not limited thereto. The connecting mechanism of the outboard motor of the present invention may be configured so that the second shaft portion provided in the upper unit is inserted into the first shaft portion provided in the lower unit.

[0112] According to the present invention, in the outboard motor in which the lower unit pivots relative to the upper unit, pressure loss in the supply passage that supplies cooling water from the lower unit to the upper unit can be reduced and cooling water can be smoothly supplied.

[0113] The present invention can be modified as appropriate without departing from the spirit or the concept of the invention as can be read from the claims and the entire specification, and outboard motors incorporating such modifications are also included in the technical concept of the present invention.